He divided the principles of things into those of which the
opposite
is unthinkable, and those of which the opposite is thinkable : he dis tinguished metaphysically, also, between necessary and contingent truths.
Windelband - History of Philosophy
and also Eth.
II.
, Ax.
III.
, and elsewhere.
* Who besides, at the outset, seems not to have known the historical origin of
being (res
' Descartes' reply to Oasaendi's objection (V. 2) ; cf. Print. Phil. I. 9.
392 The Renaissance : Natural Science Period. [Part IV.
the outer world, — three points of attachment for the three rational sciences, ethics, logic, and physics.
5. With Descartes, on the contrary, the proposition cogilo sum has not so much the meaning of an experience, as rather that of the first fundamental rational truth. Nor is its evidence that of an infer ence,1 but that of immediate intuitive certainty. The analytic method seeks here, as with Galileo, the simple, self-intelligible elements, out of which all else is to be explained ; but while the physicist discovers the perceptional elementary form of motion, which is to make com prehensible all that takes place in the corporeal world, the meta physician is hunting for the elementary truths of consciousness. In this consists the rationalism of Descartes.
This rationalism expresses itself in the fact that the superiority of self-consciousness is found in its complete clearness and distinct ness, and in the fact that Descartes propounded as his principle for the synthetic method the maxim, Everything must be true which is as clear and distinct as self-consciousness, i. e. which presents itself before the mind's vision as surely and underivably as the mind's own exist ence. " Clear " is defined by Descartes * as that which is intuitively present and manifest to the mind, " distinct " as that which is en tirely clear in itself and precisely determined. And those mental presentations — or ideas," as he calls them after the manner of later Scholasticism — which are in this sense clear and distinct, whose evidence is not to be deduced from any others, but is grounded solely in themselves, he calls innate ideas. * With this expression he indeed incidentally connects also the psycho-genetic thought that these ideas are imprinted upon the human soul by God, but for the most part he desires to give only the epistemological significance of immediate, rational evidence.
These two meanings are peculiarly mingled in Descartes' proofs for the existence of God, which form an integrant constituent of his theory of knowledge, in so far as this "idea" is the first for which,
in the synthetic procedure of his method a clearness and distinct ness or intuitive evidence of the " natural light," equal to that of self-consciousness, is claimed. The new (so-called Cartesian) proof which he introduces in this connection," has a multitude of scholastic
> Resp. ad Obj. II. i Princ. Phil. I. 45.
8 [German Idee. I follow the ordinary English usage in spelling the word as used by Descartes without a capital. ]
4 Cf. E. Grimm, D. 's Lehre ron den angeborenen Ideen (Jena, 1873), and also P. Natorp, Z>. '« Erkenntnisstheorie (Marburg, 1882). That in nut us is better translated by eingeboren than by the usual angeboren has been remarked by R. Eucken, Qeachichte und Kritik der Grundbegriffe der Oegenwart, p. 73.
* Med. III.
Chap. 2, $ 30. ] Problem of Method : Descartes. 393
assumptions. He argues that the individual self-consciousness knows itself to be finite, and therefore imperfect (according to the old identification of determinations expressing value with ontological gradations), and that this knowledge can be derived only from the conception of an absolutely perfect being (ensperfectissimum). This latter conception which we find within us must have a cause which, nevertheless, is not to be found within our own selves, nor in any other finite things. For the principle of causality requires that at least as much Reality be contained in the cause as there is in the I effect. This — in the scholastic sense — realistic principle is now applied, in analogy to Anselm's argument, to the relation of the idea in the mind (esse in intellectu or esse objective) to the Real
(esse in re or esse formaliter), in order to give the inference that we should not have the idea of a most perfect being if the idea had not been produced in us by such a being himself. This anthropologico- metaphysical proof has then with Descartes the significance that by it that former sceptical hypothetical phantom of a deceiving demon is again destroyed. For since the perfection of God involves his veracity, and it is impossible that he should so have created us that we should necessarily err, confidence in the lumen naturale, that is, in the immediate evidence of rational knowledge, is restored, and thus definitively grounded. Thus modern rationalism is introduced by Descartes by the circuitous route of Scholasticism. For this proof gives the charter for acknowledging with complete certainty as true all propositions which manifest themselves in clear and dis tinct light before the reason. Here belong, firstly, all truths of mathematics, but here belongs also the ontological proof for the existence of God. For with the same necessity of thought — thus
Descartes takes up Anselm's argument1 — with which the geometri cal propositions with regard to a triangle follow from the definition of the triangle, it follows from the mere definition of the most Real being that the attribute of existence belongs to him. The possibility of thinking God suffices to prove his existence.
In this way it follows from the criterion of clearness and distinct ness, that of finite things also, and especially of bodies, so much can be known as is clearly and distinctly perceived. But this is for Descartes the mathematical element, and is limited to the quantitative determinations, while all the sensuous-qualitative elements in percej*- tion are regarded by the philosopher as unclear and confused. On this account metaphysics and the theory of knowledge terminate for him. too, in a mathematical physics. He designates * the sensuous appre-
> Med. V. * Med. VI.
394 The. Renaissance : Natural Science Period. [Part IV.
hension of the qualitative, "imagination " {imaginatio). The appre hension of that which can be mathematically constructed he terms, on the other hand, "intellectual" knowledge (intellectio) , and strongly as he knows how to prize the help which experience gives in the former, a really scientific insight rests, in his opinion, only upon the latter.
The distinction between distinct and confused
(which goes back to Duns Scotus and farther) serves Descartes also to solve the problem of error, which results for him out of his
principle of the veracitas dei, because it does not seem possible to see how, in accordance with that principle, perfect deity could so arrange human nature as to allow it to err at all. Here Descartes helps himself1 by a peculiarly limited doctrine offreedom, which might be consistent with either Thomistic determinism or Scotist indeterminism. It is assumed, that that only clear and distinct presentations exercise so cogent and compelling power upon the mind that cannot avoid recognising them, while with reference to the unclear and confused presentations retains the boundless and groundless activity of the liberum arbitrium indifferentiae (its farthest- reaching power, which in the Scotist fashion set in analogy with the freedom of God). Thus error arises when affirmation and nega tion follow arbitrarily (without rational ground) in the case of unclear and indistinct material for judgment. * The demand which follows from this of withholding judgment in all cases where a suffi ciently clear and distinct insight not present recalls too distinctly the ancient iiroxq ("suspense") to permit us to overlook the rela tionship of this theory of error, with the doctrines of the Sceptics and Stoics as to the o-vyicaTa&o-is (cf. pp. 167, 208) In fact, Descartes recognised distinctly the will-factor in judgment (agreeing here, too, with the epistemology of Augustine and Duns Scotus), and Spinoza followed him in this, so far as to designate affirmation or denial as necessary characteristic of every idea, and thus to teach
that man cannot think without at the same time willing. *
Descartes' mathematical reform of philosophy had peculiar
fate. Its metaphysical results began rich and fruitful develop ment; its tendency as regards method, however, soon became sub-
Med. IV.
Error appears accordingly as an act of free will parallel to the act of sin, and thus as guilt the guilt or fault of self-deception. This thought was carried out particularly by Malebranche (Entret. III. f. ).
This relationship extends consistently to Descartes' ethics also. From the clear and distinct knowledge of reason follows necessarily right willing and act ing from the obscure and confused impulses of the sensibility result practically sin and theoretically error, by abuse of freedom. The ethical ideal the Socratic-Stoic ideal of the rule of reason over the sensibility.
Eth. II. , Pros. 49.
presentations
♦;931
6.
is
;
it is
a
is, it
a
a
it
. *
is
a
is
Chap. 2, § 30. ] Problem of Method : Cartesian*. 395
jected to a misunderstanding which exactly reversed its meaning. The philosopher himself desired to see the analytical method em ployed in a great proportion of instances, even in the case of par ticular problems, and thought of the synthetic method as a progress in discovery from one intuitive truth to another. His disciples, however, confounded the creatively free intellectual activity, which Descartes had in mind, with that rigidly demonstrative system of exposition which they found in Euclid's text-book of geometry. The monistic tendency of the Cartesian methodology, the fact that it set up a highest principle from which all other certainty should follow, favoured this exchange, and out of the new method of investigation there came into being again an ars demonstrandi. The ideal of philosophy appeared to be the task of developing from its funda mental principle all its knowledge as a system of as rigidly logical consistency as that with which Euclid's text-book deduces geome try with all its propositions from axioms and definitions.
A request of this sort had been answered by Descartes with a tentative sketch, though with express reference to the doubtfulness of this transfer;1 but the allurement to find the significance of mathematics for philosophical method in the circumstance, that it is the ideal of demonstrative science, seems only to have been strength ened thereby. At least, it was in this direction that the influence of the Cartesian philosophy proved strongest for the following period. In all the change of epistemological investigations until far into the eighteenth century this conception of mathematics was a firmly established axiom for all parties. Indeed, it became even a lever for scepticism and mysticism, under the direct influence of Descartes, in the case of men like Pascal. Since no other human science, so the latter argued, neither metaphysics nor the empirical disciplines, can attain mathematical evidence ; man must be modest in his efforts after rational knowledge, and must the more follow the impulse of his heart toward presageful faith, and the feeling of tact which belongs to a noble conduct of life. The Mystic Poiret
programme of universal mathematics.
Positive beginnings toward a transformation of the Cartesian
method into the Euclidean line of proof are found in the Port-Royal
> Rap. ad Ob). II.
» Pierre Daniel Hurt (1830-1721). the learned Bishop of Avranches. wtvtc Centura Philn»ophi<r Cart«tiana (1689), and Traitf de la Faibleue it V fitpril Humain (1723). Hi* Autobiography (1718) is also instructive on the point mentioned above. Cf. on him Ch. Bartholaien (Paris, 1860).
Huet,1 turned away from Cartesianism because it could not pause in its
(influenced
by Boehme), also, and the orthodox sceptic
396 The Renaissance : Natural Science Period. [Part IV.
logic and in the logical treatises of Geulincx ; but in the system of Spinoza this methodical schematism stands before us complete and perfect as from one mould. He first gave an exposition of the Car tesian philosophy " more geometrico," by developing the content of the system step by step in propositions, after first setting up defini tions and axioms. Each of these propositions was proved from the definitions, axioms, and preceding propositions ; while corollaries and scholia giving freer elucidations were added to certain of the propositions. Into this same rigid, unwieldy form Spinoza pressed his own philosophy also in the Ethics, and believed that it was thus as surely demonstrated as the Euclidean system of geometry. This presupposed not only the flawless correctness of the demonstrative process, but also an unambiguous evidence and an unassailable validity of the definitions and axioms. A look at the beginning of the Ethics (and not only of the first, but also of the following books) suffices to convince one of the naivete" with which Spinoza brings forward the complicated and condensed constructions of scholastic thought as self-evident conceptions and principles, and thereby anticipates implicitly his whole metaphysical system.
This geometrical method has, however, in Spinoza's thought — and in this consists its psycho-genetic justification — at the same time its material as well as formal significance. The fundamental re ligious conviction that all things necessarily proceed from the unitary essence of God seemed to him to require a method of philo sophical knowledge, which in the same manner should derive from the idea of God the ideas of all things. In the true philosophy the order of ideas ought to be the same as the real order of things. 1 But from this it follows of itself that the real process of the procedure of things forth from God must be thought after the analogy of the logical procedure of the consequent from its ground or reason, and thus the character of the method which Spinoza fixed upon for the problem of philosophy involved in advance the metaphysical char acter of its solution ; cf. § 31.
7. Little as men dared, in the immediately following period, to make the content of the Spinozistic philosophy their own, its method ical form exercised, nevertheless, an impressive influence : and the more the geometrical method became settled in the philosophy of the schools, the more the syllogistic procedure entered again with since all knowledge was to be deduced from the highest truths by
The view that true knowledge as genetic definition must repeat the process by which its object arises was carried out especially by Tschirnhausen, who did not shrink from the paradox that a complete definition of laughter must be able to produce laughter itself (ited. Ment. , 67 f. )
!
1
it,
Chap. 2, $ 30. ] Problem of Method : Spinoza, Leibniz. 397
inferences. Especially did the mathematically schooled Cartesians in Germany take up the geometrical method along this line : this was done by Jung and Weigel, and the academic impulse to the preparation of text-books found in this method a form with which it could have the utmost sympathy. In the eighteenth cen tury Christian Wolff (cf. Part V. ) pursued this line in the most comprehensive manner with his Latin text-books, and for the sys- tematisation of a firmly established and clearly thought out material there could be in fact no better form. This was shown when Puffen-
dorf undertook to deduce the entire system of Natural Right by the geometrical method, as a logical necessity from the single principle of the need of society.
When this view was in process of coming into existence Leibniz came into sympathy with it under the especial influence of Erhard Weigel, and was at the beginning one of its most consistent sup
He not only made the jest of giving this unwonted garb to a political brochure,1 but was seriously of the opinion that philo sophical controversies would find their end for the first time when a philosophy could once make its appearance in as clear and certain a form as that of a mathematical calculation. *
Leibniz pursued this thought very energetically. The stimulus of Hobbes, who also — though with quite another purpose, cf. § 31, 2 — declared thinking to be a reckoning with the conceptional signs of things, may have been added ; the Art of Lull and the pains which Giordano Bruno had taken with its improvement were well known to him. In Cartesian circles, also, the thought of transform ing the mathematical method to a regular art of invention had been
much discussed : besides Joachim Jung, the Altorf Professor Joh. Christopher Sturm,3 had also exercised an influence upon Leibniz in this respect. Finally, the thought of expressing the fundamental metaphysical conceptions, and likewise the logical operations of their combination after the manner of the mathematical sign-lan guage by definite characters, seemed to offer the possibility of writ ing a philosophical investigation in general formula1, and by this means raising it beyond the capability of being expressed in a
definite language — an effort toward a universally scientific lan guage, a " Lingua Adamica," which likewise appeared at the time
* In the pseudonymous Specimen drmonMratinnum politieanim pro rr<>r Polo- norum tligendo (MW9), he proved by "geometrical mt-tliod" in sixty proposi tions and demonstration* that the Count Palatine of Neuhiiix imutt be chosen king of the Pole*. -^
* De Srlrntin Vmvertali ten Calrulo Phllotophico (U>«4). ' * The author of a Compendium Univrrtalium sen Metaphyiicu KurlUIn*
regular
porters.
The Renaissance : Natural Science Period. [Part IV.
of Leibniz in numerous supporters. 1 So, too, Leibniz busied himself to an extraordinary degree with the thought of a characteristica uni versalis, and a method of philosophical calculus. 2
The essential outcome of these strange endeavours was, that an attempt was necessarily made to establish those highest truths, from the logical combination of which all knowledge was to be deduced. So Leibniz, like Galileo and Descartes, must proceed to search out that which, as immediately and intuitively certain, forces itself upon the mind as self-evident, and by its combinations grounds all derived knowledge. In the course of these reflections Leibniz stumbled upon the discovery3 (which Aristotle had made before him), that there are two completely different kinds of this intuitive knowledge : universal truths self-evident to reason, and facts of experience. The one class has timeless validity ; the other, validity for a single instance : viritis iternelles and vtrite's de fait. Both have in common that they are intuitively certain, i. e. are certain in them selves and not by deduction from anything else ; they are called, therefore, prima veritates, or, also, primes possibiiitates, because in them the possibility of all that is derivative has its ground. For the " possibility " of a conception is known either by a " causal definition " which derives the same from the first possibilities, that is, a priori; or by the immediate experience of its actual existence, that is, a, posteriori.
These two kinds of "primitive truths" — the rational and the empirical, as we see — Leibniz attached in a very interesting manner to the two Cartesian marks of intuitive self-evidence, clearness and distinctness. To this end he shifts to a slight extent the meaning of both expressions. 4 That idea is clear which is surely distin guished from all others and so is adequate for the recognition of its object; that idea is distinct which is clear even to its particular constituent parts and to the knowledge of their combination. According to this, the a priori, "geometrical" or "metaphysical" eternal truths are clear and distinct ; while on the other hand the a posteriori, or the truths relating to facts, are clear, indeed, but not distinct. Hence the former are perfectly transparent, conjoined with the conviction of the impossriblity of the opposite, while in the case of the latter the opposite is thinkable. In the case of the former the intuitive certainty rests upon the Principle of Contradic
1 Such attempts had been projected by J. J. Becker (1661 ), G. Dalgarn (1661), Athanasius Kircher (1663), and J. Wilkins ( 1668).
* Cf. A. Trendelenburg, Historische Beitrage zu Philosophic, Vols. II. , III. 8 Meditationes de Cognitions Veritute et Idris (1684).
* lb. at the beginning, Erd's. ed. , p. 79.
Chap. 2, § 31. ] Substance and Causality. 399
twn; in the case of the latter the possibility guaranteed by the actual fact needs still an explanation in accordance with the Prin
ciple of Sufficient Reason.
At the beginning, Leibniz intended this distinction only with
reference to the imperfection of the human understanding. In the case of rational truths we see into the impossibility of the opposite ; with empirical truths this is not the case, and we must content our selves with establishing their actuality : ' but the latter also, in the natura rerum and for the divine understanding, are so grounded that the opposite is impossible, although it remains thinkable for us. If Leibniz compared this distinction with that of commensur able and incommensurable magnitudes, he meant at the beginning that incommensurability lies only in man's limited knowing capacity. But in the course of his development this antithesis became for him an absolute one ; it gained metaphysical significance. Leibniz now distinguished realiter between an unconditional necessity, which involves the logical impossibility of the opposite, and a conditional necessity, which has " only " the character of a matter of fact.
He divided the principles of things into those of which the opposite is unthinkable, and those of which the opposite is thinkable : he dis tinguished metaphysically, also, between necessary and contingent truths. This, however, cohered with metaphysical motives, which arose from an after-working of the Scotist theory of the contin gency of the finite, and overthrew the geometrical method.
§ 31. Substance and Causality.
The real [as contrasted with formal] result of the new methods was in metaphysics, as in natural science, a transformation of the fundamental ideas of the nature of things, and of the mode of their connection in the processes of Nature : the conceptions of sub stance and causality acquired a new content. Hut this change could not proceed so radically in metaphysics as in natural science. In this latter more limited realm, after the Galilean principle had once been found, it was possible in a certain measure to begin ab ovo and produce a completely new theory : in the more general philo sophical doctrines the power and authority of tradition were much too great to make it possible or permissible that it should be completely set aside.
This distinction asserted itself already in connection with the delicate relation sustained to religious conceptions. Natural science
1 The Aristotelian distinction of Mti and An,
400 The Renaissance : Natural Science Period. (Taet IV.
could isolate itself absolutely from theology, and maintain toward it an attitude of complete indifference : metaphysics, by its concep tion of the deity and by its theory of the mental or spiritual world, was brought again and again into hostile or friendly contact with the religious sphere of ideas. A Galileo declared that the investigations of physics, whatever their result might be, had not the least thing to do with the teaching of the Bible,1 and a Newton was not prevented by his mathematical natural philosophy from burying himself with the most ardent piety in the mysteries of the Apocalypse. But the metaphysicians, however indifferent their thought as regards religion, and however strictly they might prose cute their science in the purely theoretical spirit, were still always obliged to consider that they had to do with objects concerning which the Church doctrine was fixed. This gave modern philosophy a somewhat delicate position : mediaeval philosophy had brought to the objects of Church dogma an essentially religious interest of its own as well ; modern philosophy regarded them, if at all, from the theoretical standpoint only. Hence those felt themselves most secure who, like Bacon and Hobbes, restricted philosophy also entirely to natural research, declined to enter upon a metaphysics proper, and were willing to let dogma speak the only words with regard to the deity and the super-sensible destiny of man. Bacon did this with large words behind which it is difficult to recognise his true disposition ; 2 Hobbes rather let it be seen that his natural istic opinion, like the Epicurean, saw in ideas as to the supernatural a superstition resting upon a defective knowledge of Nature, — a superstition which by the regulation of the state becomes the bind ing authority of religion. 8 Much more difficult, however, was the position of those philosophers who held fast to the metaphysical conception of the deity in their very explanation of Nature ; Des cartes' whole literary activity is filled with an anxious caution directed toward avoiding every offence to religion, while Leibniz could attempt to carry through in a much more positive manner the conformity of his metaphysics to religion ; and on the other hand the example of Spinoza showed how dangerous it was if philosophy openly brought to the front the difference between its conception of God and the dogmatic conception.
1. The main difficulty of the case inhered in the circumstance that the new methodical principle of mechanics excluded all tracing of
i Cf. the letter to the Grand Duchess Christine, Op. II. 26 ft*.
s De Augm. Scient. IX. , where the supernatural and incomprehensible is set
forth as the characteristic and serviceable quality of faith. * Leviathan, I. 6 ; cf. the drastic expression, ib, IV. 32.
Chap. 2, § 31. ] Substance and Causality : Bacon. 401
corporeal phenomena back to spiritual forces. Nature was despiritu- alised ; science would see in it nothing but the movements of smallest bodies, of which one is the cause of the other. No room remained for the operation of supernatural powers. So first of all, at one stroke, magic, astronomy, and alchemy, in which the Neo-Platonic ghosts and spirits had held sway, became for science a standpoint of the past Leonardo had already demanded that the phenomena of the external world should be explained by natural causes only ; the great systems of the seventeenth century without exception recognise only such, and a Cartesian, Balthasar Bekker, wrote a book ' to show that in accordance with the principles of modern science, all appear ances of ghosts, conjurations, and magic arts must be reckoned as injurious errors, — a word of admonition which was very much in
place in view of the luxuriant superstition of the Renaissance.
But with the spirits, teleology, also, was obliged to give place.
The explanation of natural phenomena by their purposiveness always came ultimately in some way or other to the thought of a spiritual creation or ordering of things, and so was contradictory to the principle of mechanics. At this point the victory of the system of Democritus over the natural philosophy of Plato and Aristotle was most palpable ; this, too, was emphasised most forcibly by the new philosophy. Bacon counted the teleological mode of regarding Nature as one of the idols, and, indeed, as one of the dangerous idols of the tribe, — the fundamental errors which become a source of illusion to man through his very nature : he taught that
philosophy has to do only with formal or efficient causes, and ex pressed his restriction of philosophy to physics and his rejection of metaphysics precisely by saying that the explanation of Nature is
if it concerns causm efficientes, metaphysics if it concerns causae finale*} In the case of Hobbes, who was the disciple of Bacon and Galileo, the same view is self-explaining. But Descartes, also, desires to see all final causes kept at a distance from the explanation of Nature — he declares it audacious to desire to know the purposes of God. ' Much more open, and keenest by far, is the
polemic of Spinoza* against the anthropomorphism of teleology. In view of his idea of God and God's relation to the world, it is absurd to speak of ends of the deity, and especially of such as have reference to men ; where all follows with eternal necessity from the essential nature of the deity, there is no room for an activity accord ing to ends. The English Neo-Platonists, such as Cudworth Shd
« Balthaur Bekker (1634-1898), De Betoeerte Wereld (1690). * De Angm. III. 4. > Med. IV.
* Cf. principally Kih. I. Append.
physics
402 The. Renaissance : Natural Science Period. [Part IV.
Henry More, combated this fundamental mechanico-antiteleological feature of the new metaphysics with all the eloquence of the old arguments, but without success. The teleological conviction was obliged to renounce definitively the claim of affording scientific explanation of particular phenomena, and only in the metaphysical conception of the whole did Leibniz (cf. below, No. 8), and similarly a part of the English students of Nature, find ultimately a satisfac
tory adjustment between the opposing principles.
With the exclusion of the spiritual from the explanation of
Nature, still a third element of the old view of the world fell away, viz. the thought of the difference in kind and in value of the spheres of Nature, as it had been embodied most distinctly in the Neo-Platonic graded realm of things, following the ancient Pythagorean precedent. In this respect the fantastic natural philosophy of the Renaissance had already done a forcible work of preparation. The Stoic doctrine of the omnipresence of all sub stances at every point of the universe had been revived by Nicolaus Cusanus ; but it was in connection with the victory of the Coperni- can system, as we see in Bruno, that the idea of the homogeneity
of all parts of the universe first completely forced its way to recogni
tion. The sublunary world could no longer be contrasted as the realm of imperfection, with the more spiritual spheres of the stellar heaven; matter and motion are alike in both. It was from this thought that Kepler and Galileo proceeded, and it became complete when Newton recognised th« identity of force in the fall of the apple and the revolution of the stars. For modern science, the old distinction in essence and in value between heaven and earth exists no longer. The universe is one in nature throughout. This same view, moreover, presented itself in opposition to the Aristotelian and Thomistic development system of Matters and Forms. It did away with the whole army of lower and higher forces — the much combated qualitates occulta; ; it recognised the mechanical principle of motion as the only ground of explanation for all phenomena, and therefore, removed also the distinction in principle between the ani mate and the inanimate. Though here Neo-Platonism had co operated toward overcoming this antithesis by its view of the animation of the entire universe, the reverse task now arose for the Galilean mechanics, namely, that of explaining mechanically the phenomena of life also. The discovery of the mechanism of the circulation of the blood by Harvey l (1626) gave to this tendency a
1 In which he had been anticipated by Michael Servetus (burned 1553 in Geneva by Calvin's instrumentality).
•
Chap. 2, §31. ] Substance and Causality: Descartes, Locke. 403
vigorous impulse ; Descartes expressed it in principle in his state ment that the bodies of animals are to be regarded scientifically as most complex automata, and their vital activities as mechanical
Hobbes and Spinoza carried out this thought more exactly ; a zealous study of reflex motions began in the medical schools of France and the Netherlands, and the conception of the soul as vital force became completely disintegrated. Only the Platonists and the adherents of the vitalism of Paracelsus and Boehme, such as Van Hehnont, held fast to this conception in the old manner.
This mechanistic despiritualisation of Nature corresponded completely to that dualistic theory of the world, which from episte- mological motives had been in course of preparation in terministic Nominalism, — the theory of total difference between the inner and the outer icorld. To the knowledge of their qualitative difference was now added that of their real and causal separateness. The world of bodies appeared not only quite different in kind from that of mind, but also as entirely sundered from in its existence and in the course of its motions. The doctrine of the intellectuality of the sense qualities, revived in the philosophy of the Renaissance by the Humanists, had contributed an extraordinary amount toward sharpening the above antithesis. The doctrine tliat colours, tones, smells, tastes, and qualities of pressure, heat, and touch are not real qualities of things, but only signs of such in the mind, had passed over from the Sceptical and Epicurean literature into most of the doctrines of modern philosophy with repetition of the ancient illustrations. Vives, Montaigne, Sanchez, and Campanella were at one in this Galileo, Hobbes, and Descartes revived the teaching of Democritus, that to these qualitative differences of perception noth
ing but quantitative differences correspond in the natura rerum, and this in such way that the former are the inner modes of mentally representing the latter. Descartes regarded sense qualities as ob scure and confused ideas, while the conception of the quantitative determinations of the outer world, on account of its mathematical character, was for him the only clear and distinct idea of them.
According to Descartes, therefore, not only the sensuous feelings, but also the contents of sensation, belong not to the spatial, but to the psychical world only, and represent in this sphere the geomet rical structures of which they are the signs. In our examination of an individual object we can,1 to be sure, gain a knowledge of this
Ct. Med. VI. which allows pcrliapt the plainest view of the very clow relation which I>>-«c»rt< »' [I'lvsicil ■<•arch had t<>experience.
processes.
r
a
»
'1.
; a
a
it
404 The Renaissance : Natural Science Period. [Part IV.
true mathematical essence of bodies only by the aid of perceptions, and in these perceptions the true mathematical essence is always alloyed with the qualitative elements of the "imagination. " But just in this consists the task of physical research, to dissolve out this real essence of bodies from the subjective modes of our mental representation by means of reflection upon the clear and distinct ele ments of perception. John Locke, who later adopted and made popular this view of Descartes, designated ' those qualities which belong to bodies in themselves as primary, and called those sec ondary, on the other hand, which belong to a body only by virtue of its action upon our senses. 2 Descartes allowed as primary qualities only shape, size, position, and motion, so that for him the physical body coincided with the mathematical (cf. below, No. 4). In order to maintain a distinction between the two, Henry More,3 on the con trary, demanded that impenetrability, regarded as the property of filling space, should also be reckoned to the essential nature of bodies, and Locke,4 in accordance with this view, took up " solidity " into the class of primary qualities.
With Hobbes 5 these thoughts become modified more in accordance with the terministic conception. He regards space (as phantasma rei existentis) and time (as phantasma motus) as also modes of men tal representation, and it is just because we can therefore construct these ourselves that mathematical theory has the advantage of being the sole rational science. But instead of drawing phenomenalistic conclusions from this premise, he argues that philosophy can treat only of bodies, and must leave everything spiritual to revelation. Scientific thought consequently consists, for him, only in the imma nent combination of signs. These are partly involuntary in percep tions, partly arbitrary in words (similarly Occam, cf. § 27, 4). It is only by means of the latter that general conceptions and proposi tions become possible. Our thinking is hence a reckoning with verbal signs. It has its truth in itself and stands as something completely heterogeneous by the side of the outer world to which it relates.
3. All these suggestions become compressed in the system of Descartes to form the doctrine of the dualism of substances. The analytic method was intended to discover the simple elements of reality which were self-explanatory and not susceptible of farther
1 Essay, Human Understanding, II. 8, § 23 f.
a As tertiary qualities, Locke added further the " powers " for the operation of one body upon others.
•Desc. (Euv. (C), X. pp. 181 ff.
« Essay, II. 4.
6 Human Nature, chs. 2-6 ; Leviathan, cha. 4 ff.
Chap. 2, § 31. ] Substance and Causality : Hobbes, Descartes. 405
deduction. Descartes discovered that all that can be experienced is a species either of spatial or of conscious Being or existence. Spa- tiality, or the quality of filling space, and consciousness (" extension " and "thought" according to the usual translation of extensio and cogi- tatio) are the ultimate, simple, original attributes of reality. All that is is either spatial or conscious. For these two prime predi cates are related disjunctively. What is spatial is not conscious ; what is conscious is not spatial. The self-certainty of mind is only that of the personality as a conscious being. Bodies are real in so far as they have in themselves the quantitative determinations of spatial existence and change, of extension and motion, All things are either bodies or minds ; substances are either spatial or con scious : res extensat and res cogitantes.
The world falls thus into two completely different and completely separated realms : that of bodies and that of minds. But in the background of this dualism there stands in the thought of Descartes the conception of the deity as the ens perfectissimum or perfect sub stance. Bodies and minds are finite things; God is infinite Being. 1 The Meditations leave no doubt as to the fact that Descartes ac cepted the conception of God quite in accordance with the inter
pretation of scholastic Realism. The mind in its own Being, which it recognises as a limited and imperfect one, apprehends with the same intuitive certainty the Reality of the perfect, infinite Being also (cf. above, $ 30, 5). To the ontological argument is added the relation of God and the world in the form brought forward by Nicolaus Cusanus, namely, that of the antithesis of the infinite and the finite. But the above-mentioned relationship with the Realism of the Middle Ages appears most distinctly in the development of metaphysics that succeeded Descartes : for the pantheistic conse quences of this presupposition, which had been carefully held back in the scholastic period, were now spoken out with complete clear ness and sureness. And if we find in the doctrines of Descartes' successors a strong similarity with those which in the Middle Ages could lead but a more or less repressed existence, this is intelligible »-ven without the assumption of a direct historical dependence, merely by the pragmatic connection and the logical necessity of the conclusions.
4- The common metaphysical name of "substance," applied to God in the infinite sense, and to minds and bodies in a finite sense, could not permanently cover the problems which were hidden be-
• So likewise Malebrancbe said (Rrrh. III. 2. 0 a. K. ) that Ood could properly ba called only Celui qui est, be is ritre sans restriction, tout ttre injlni tit vairertei.
406 The Renaissance : Natural Science Period. [Part IV.
neath it. The conception of substance had come into a state of flux, and needed " further re-shaping. It had almost lost touch with the idea of thing," the category of inherence ; for just the combi nation of a multiplicity of determinations into the idea of a unitary concrete entity, which is essential to this category, was completely lacking in Descartes' conception of finite substances, since these were held to be characterised by one fundamental quality, spatiality or consciousness. All else that was found in substances must there fore be regarded as a modification of its fundamental quality, of its attribute. All qualities and states of bodies are modes of their spa tiality or extension: all qualities and states of mind are modes of consciousness (modi cogitandi).
It is involved in this that all particular substances belonging to either class, all bodies on the one hand and all minds on the other, are alike in their essence, their constitutive attribute. But from this it is only a step farther to the idea in which this likeness is thought as metaphysical identity. All bodies are spatial, all minds are conscious ; individual bodies are distinguished from one another only by different modes of spatiality (form, size, situation, motion) ; individual minds are distinguished from one another only by differ ent modes of consciousness (ideas, judgments, activities of will). Individual bodies are modes of spatiality, individual minds are modes of consciousness. In this way the attribute obtains meta physical preponderance over individual substances, which now appear as its modifications ; the res extensas become modi extension's; the res cogitantes, modi cogitationis.
Descartes himself drew this conclusion only in the domain of natr ural philosophy, to which in general he restricted the carrying out of his metaphysical doctrine in its principles. Here, however, the general conception of modification took on, of itself, a definite sig nificance, and one capable of apprehension by perception or imagina tion, viz. that of limitation (determinatio) . Bodies are parts of space, limitations of the universal space-filling quality or extension. 1 Hence for Descartes the conception of body coincides with that of a limited spatial magnitude. A body as regards its true essence, a portion of space. The elements of the corporeal world are the " corpuscles,"
Cf. Print. Phil. II. f. , where, at the same time, appears quite clearly that this relation of the individual body to universal space made equivalent to that of individual and species.
For the corpuscular theory, Descartes found many suggestions in Bacon, Hobbes, Basso, Sennert, and others. The variety in the development of this theory, which rests upon the dialectic between the mathematical and the physi cal momenta, has more interest for natural science than for philosophy. An excellent exposition found in Lasswitz, GescMchte der Atomistik.
is
21
it is
9
'
is,
Chap. 2, § 31. ] Substance and Causality : Malebrancfie. 407
i. e. the firm spatial particles which realiter are no longer divisible : as mathematical structures, however, they are infinitely divisible; that is, there are no atoms. From these presuppositions follow, likewise, for Descartes, the impossibility of empty space, and the infinitude of the corporeal world.
For the mental world the analogous claim was pronounced by Malebranche. In connection with the epistemological motives (cf. below, No. 8) which made it seem to him that no knowledge of things is possible except in God, he came ' to the conception of the raisou universelle, which, as being alike in all individual minds, can not belong to the modes of the finite mind, but is rather that of which finite minds are themselves modifications, and can, just on this account, be none other than an attribute of God. God is in so far the " place of minds " or spirits, just as space is the place of bodies. Here, also, as the expression proves, the relation which obtains in conceptions between the universal and the particular underlies the thought, and following the analogy of the Cartesian conception of space and body this relation is thought in percep tional or picturate terms as participation. * All human insight is a participation in the infinite Reason, all ideas of finite things are but determinations of the idea of God, all desires directed toward the particular object are but participations in that love toward God as the ground of its essence and life, which necessarily dwells in the finite mind. To be sure, Malebranche came into a very critical situation by thus making the finite mind disappear completely in the universal divine mind, as its modification. For how, in accord ance with this, should he explain the self-subsistence and self- activity which it seemed were quite notoriously present in those inclinations and volitions of man which opposed God ? In this difficulty nothing availed but the word " freedom," in using which Malebranche was indeed obliged to confess that freedom was an impenetrable mystery. 3
5. In this course of thought pursued by Malebranche appears clearly the inevitable logical consistency with which the attributes, which were regarded by Descartes as the common essence belonging to either of the two classes of finite substances, could ultimately be thought only as the attributes of the infinite substance or deity. Hut precisely in this point consists the fundamental motive of Spi- nozism, which developed along this line out of Cartesianism directly
and at the outset, and at the same time developed to the farthest
1 Rtck. de la Vtr. III. 2, 8 ; Sntret.
* Who besides, at the outset, seems not to have known the historical origin of
being (res
' Descartes' reply to Oasaendi's objection (V. 2) ; cf. Print. Phil. I. 9.
392 The Renaissance : Natural Science Period. [Part IV.
the outer world, — three points of attachment for the three rational sciences, ethics, logic, and physics.
5. With Descartes, on the contrary, the proposition cogilo sum has not so much the meaning of an experience, as rather that of the first fundamental rational truth. Nor is its evidence that of an infer ence,1 but that of immediate intuitive certainty. The analytic method seeks here, as with Galileo, the simple, self-intelligible elements, out of which all else is to be explained ; but while the physicist discovers the perceptional elementary form of motion, which is to make com prehensible all that takes place in the corporeal world, the meta physician is hunting for the elementary truths of consciousness. In this consists the rationalism of Descartes.
This rationalism expresses itself in the fact that the superiority of self-consciousness is found in its complete clearness and distinct ness, and in the fact that Descartes propounded as his principle for the synthetic method the maxim, Everything must be true which is as clear and distinct as self-consciousness, i. e. which presents itself before the mind's vision as surely and underivably as the mind's own exist ence. " Clear " is defined by Descartes * as that which is intuitively present and manifest to the mind, " distinct " as that which is en tirely clear in itself and precisely determined. And those mental presentations — or ideas," as he calls them after the manner of later Scholasticism — which are in this sense clear and distinct, whose evidence is not to be deduced from any others, but is grounded solely in themselves, he calls innate ideas. * With this expression he indeed incidentally connects also the psycho-genetic thought that these ideas are imprinted upon the human soul by God, but for the most part he desires to give only the epistemological significance of immediate, rational evidence.
These two meanings are peculiarly mingled in Descartes' proofs for the existence of God, which form an integrant constituent of his theory of knowledge, in so far as this "idea" is the first for which,
in the synthetic procedure of his method a clearness and distinct ness or intuitive evidence of the " natural light," equal to that of self-consciousness, is claimed. The new (so-called Cartesian) proof which he introduces in this connection," has a multitude of scholastic
> Resp. ad Obj. II. i Princ. Phil. I. 45.
8 [German Idee. I follow the ordinary English usage in spelling the word as used by Descartes without a capital. ]
4 Cf. E. Grimm, D. 's Lehre ron den angeborenen Ideen (Jena, 1873), and also P. Natorp, Z>. '« Erkenntnisstheorie (Marburg, 1882). That in nut us is better translated by eingeboren than by the usual angeboren has been remarked by R. Eucken, Qeachichte und Kritik der Grundbegriffe der Oegenwart, p. 73.
* Med. III.
Chap. 2, $ 30. ] Problem of Method : Descartes. 393
assumptions. He argues that the individual self-consciousness knows itself to be finite, and therefore imperfect (according to the old identification of determinations expressing value with ontological gradations), and that this knowledge can be derived only from the conception of an absolutely perfect being (ensperfectissimum). This latter conception which we find within us must have a cause which, nevertheless, is not to be found within our own selves, nor in any other finite things. For the principle of causality requires that at least as much Reality be contained in the cause as there is in the I effect. This — in the scholastic sense — realistic principle is now applied, in analogy to Anselm's argument, to the relation of the idea in the mind (esse in intellectu or esse objective) to the Real
(esse in re or esse formaliter), in order to give the inference that we should not have the idea of a most perfect being if the idea had not been produced in us by such a being himself. This anthropologico- metaphysical proof has then with Descartes the significance that by it that former sceptical hypothetical phantom of a deceiving demon is again destroyed. For since the perfection of God involves his veracity, and it is impossible that he should so have created us that we should necessarily err, confidence in the lumen naturale, that is, in the immediate evidence of rational knowledge, is restored, and thus definitively grounded. Thus modern rationalism is introduced by Descartes by the circuitous route of Scholasticism. For this proof gives the charter for acknowledging with complete certainty as true all propositions which manifest themselves in clear and dis tinct light before the reason. Here belong, firstly, all truths of mathematics, but here belongs also the ontological proof for the existence of God. For with the same necessity of thought — thus
Descartes takes up Anselm's argument1 — with which the geometri cal propositions with regard to a triangle follow from the definition of the triangle, it follows from the mere definition of the most Real being that the attribute of existence belongs to him. The possibility of thinking God suffices to prove his existence.
In this way it follows from the criterion of clearness and distinct ness, that of finite things also, and especially of bodies, so much can be known as is clearly and distinctly perceived. But this is for Descartes the mathematical element, and is limited to the quantitative determinations, while all the sensuous-qualitative elements in percej*- tion are regarded by the philosopher as unclear and confused. On this account metaphysics and the theory of knowledge terminate for him. too, in a mathematical physics. He designates * the sensuous appre-
> Med. V. * Med. VI.
394 The. Renaissance : Natural Science Period. [Part IV.
hension of the qualitative, "imagination " {imaginatio). The appre hension of that which can be mathematically constructed he terms, on the other hand, "intellectual" knowledge (intellectio) , and strongly as he knows how to prize the help which experience gives in the former, a really scientific insight rests, in his opinion, only upon the latter.
The distinction between distinct and confused
(which goes back to Duns Scotus and farther) serves Descartes also to solve the problem of error, which results for him out of his
principle of the veracitas dei, because it does not seem possible to see how, in accordance with that principle, perfect deity could so arrange human nature as to allow it to err at all. Here Descartes helps himself1 by a peculiarly limited doctrine offreedom, which might be consistent with either Thomistic determinism or Scotist indeterminism. It is assumed, that that only clear and distinct presentations exercise so cogent and compelling power upon the mind that cannot avoid recognising them, while with reference to the unclear and confused presentations retains the boundless and groundless activity of the liberum arbitrium indifferentiae (its farthest- reaching power, which in the Scotist fashion set in analogy with the freedom of God). Thus error arises when affirmation and nega tion follow arbitrarily (without rational ground) in the case of unclear and indistinct material for judgment. * The demand which follows from this of withholding judgment in all cases where a suffi ciently clear and distinct insight not present recalls too distinctly the ancient iiroxq ("suspense") to permit us to overlook the rela tionship of this theory of error, with the doctrines of the Sceptics and Stoics as to the o-vyicaTa&o-is (cf. pp. 167, 208) In fact, Descartes recognised distinctly the will-factor in judgment (agreeing here, too, with the epistemology of Augustine and Duns Scotus), and Spinoza followed him in this, so far as to designate affirmation or denial as necessary characteristic of every idea, and thus to teach
that man cannot think without at the same time willing. *
Descartes' mathematical reform of philosophy had peculiar
fate. Its metaphysical results began rich and fruitful develop ment; its tendency as regards method, however, soon became sub-
Med. IV.
Error appears accordingly as an act of free will parallel to the act of sin, and thus as guilt the guilt or fault of self-deception. This thought was carried out particularly by Malebranche (Entret. III. f. ).
This relationship extends consistently to Descartes' ethics also. From the clear and distinct knowledge of reason follows necessarily right willing and act ing from the obscure and confused impulses of the sensibility result practically sin and theoretically error, by abuse of freedom. The ethical ideal the Socratic-Stoic ideal of the rule of reason over the sensibility.
Eth. II. , Pros. 49.
presentations
♦;931
6.
is
;
it is
a
is, it
a
a
it
. *
is
a
is
Chap. 2, § 30. ] Problem of Method : Cartesian*. 395
jected to a misunderstanding which exactly reversed its meaning. The philosopher himself desired to see the analytical method em ployed in a great proportion of instances, even in the case of par ticular problems, and thought of the synthetic method as a progress in discovery from one intuitive truth to another. His disciples, however, confounded the creatively free intellectual activity, which Descartes had in mind, with that rigidly demonstrative system of exposition which they found in Euclid's text-book of geometry. The monistic tendency of the Cartesian methodology, the fact that it set up a highest principle from which all other certainty should follow, favoured this exchange, and out of the new method of investigation there came into being again an ars demonstrandi. The ideal of philosophy appeared to be the task of developing from its funda mental principle all its knowledge as a system of as rigidly logical consistency as that with which Euclid's text-book deduces geome try with all its propositions from axioms and definitions.
A request of this sort had been answered by Descartes with a tentative sketch, though with express reference to the doubtfulness of this transfer;1 but the allurement to find the significance of mathematics for philosophical method in the circumstance, that it is the ideal of demonstrative science, seems only to have been strength ened thereby. At least, it was in this direction that the influence of the Cartesian philosophy proved strongest for the following period. In all the change of epistemological investigations until far into the eighteenth century this conception of mathematics was a firmly established axiom for all parties. Indeed, it became even a lever for scepticism and mysticism, under the direct influence of Descartes, in the case of men like Pascal. Since no other human science, so the latter argued, neither metaphysics nor the empirical disciplines, can attain mathematical evidence ; man must be modest in his efforts after rational knowledge, and must the more follow the impulse of his heart toward presageful faith, and the feeling of tact which belongs to a noble conduct of life. The Mystic Poiret
programme of universal mathematics.
Positive beginnings toward a transformation of the Cartesian
method into the Euclidean line of proof are found in the Port-Royal
> Rap. ad Ob). II.
» Pierre Daniel Hurt (1830-1721). the learned Bishop of Avranches. wtvtc Centura Philn»ophi<r Cart«tiana (1689), and Traitf de la Faibleue it V fitpril Humain (1723). Hi* Autobiography (1718) is also instructive on the point mentioned above. Cf. on him Ch. Bartholaien (Paris, 1860).
Huet,1 turned away from Cartesianism because it could not pause in its
(influenced
by Boehme), also, and the orthodox sceptic
396 The Renaissance : Natural Science Period. [Part IV.
logic and in the logical treatises of Geulincx ; but in the system of Spinoza this methodical schematism stands before us complete and perfect as from one mould. He first gave an exposition of the Car tesian philosophy " more geometrico," by developing the content of the system step by step in propositions, after first setting up defini tions and axioms. Each of these propositions was proved from the definitions, axioms, and preceding propositions ; while corollaries and scholia giving freer elucidations were added to certain of the propositions. Into this same rigid, unwieldy form Spinoza pressed his own philosophy also in the Ethics, and believed that it was thus as surely demonstrated as the Euclidean system of geometry. This presupposed not only the flawless correctness of the demonstrative process, but also an unambiguous evidence and an unassailable validity of the definitions and axioms. A look at the beginning of the Ethics (and not only of the first, but also of the following books) suffices to convince one of the naivete" with which Spinoza brings forward the complicated and condensed constructions of scholastic thought as self-evident conceptions and principles, and thereby anticipates implicitly his whole metaphysical system.
This geometrical method has, however, in Spinoza's thought — and in this consists its psycho-genetic justification — at the same time its material as well as formal significance. The fundamental re ligious conviction that all things necessarily proceed from the unitary essence of God seemed to him to require a method of philo sophical knowledge, which in the same manner should derive from the idea of God the ideas of all things. In the true philosophy the order of ideas ought to be the same as the real order of things. 1 But from this it follows of itself that the real process of the procedure of things forth from God must be thought after the analogy of the logical procedure of the consequent from its ground or reason, and thus the character of the method which Spinoza fixed upon for the problem of philosophy involved in advance the metaphysical char acter of its solution ; cf. § 31.
7. Little as men dared, in the immediately following period, to make the content of the Spinozistic philosophy their own, its method ical form exercised, nevertheless, an impressive influence : and the more the geometrical method became settled in the philosophy of the schools, the more the syllogistic procedure entered again with since all knowledge was to be deduced from the highest truths by
The view that true knowledge as genetic definition must repeat the process by which its object arises was carried out especially by Tschirnhausen, who did not shrink from the paradox that a complete definition of laughter must be able to produce laughter itself (ited. Ment. , 67 f. )
!
1
it,
Chap. 2, $ 30. ] Problem of Method : Spinoza, Leibniz. 397
inferences. Especially did the mathematically schooled Cartesians in Germany take up the geometrical method along this line : this was done by Jung and Weigel, and the academic impulse to the preparation of text-books found in this method a form with which it could have the utmost sympathy. In the eighteenth cen tury Christian Wolff (cf. Part V. ) pursued this line in the most comprehensive manner with his Latin text-books, and for the sys- tematisation of a firmly established and clearly thought out material there could be in fact no better form. This was shown when Puffen-
dorf undertook to deduce the entire system of Natural Right by the geometrical method, as a logical necessity from the single principle of the need of society.
When this view was in process of coming into existence Leibniz came into sympathy with it under the especial influence of Erhard Weigel, and was at the beginning one of its most consistent sup
He not only made the jest of giving this unwonted garb to a political brochure,1 but was seriously of the opinion that philo sophical controversies would find their end for the first time when a philosophy could once make its appearance in as clear and certain a form as that of a mathematical calculation. *
Leibniz pursued this thought very energetically. The stimulus of Hobbes, who also — though with quite another purpose, cf. § 31, 2 — declared thinking to be a reckoning with the conceptional signs of things, may have been added ; the Art of Lull and the pains which Giordano Bruno had taken with its improvement were well known to him. In Cartesian circles, also, the thought of transform ing the mathematical method to a regular art of invention had been
much discussed : besides Joachim Jung, the Altorf Professor Joh. Christopher Sturm,3 had also exercised an influence upon Leibniz in this respect. Finally, the thought of expressing the fundamental metaphysical conceptions, and likewise the logical operations of their combination after the manner of the mathematical sign-lan guage by definite characters, seemed to offer the possibility of writ ing a philosophical investigation in general formula1, and by this means raising it beyond the capability of being expressed in a
definite language — an effort toward a universally scientific lan guage, a " Lingua Adamica," which likewise appeared at the time
* In the pseudonymous Specimen drmonMratinnum politieanim pro rr<>r Polo- norum tligendo (MW9), he proved by "geometrical mt-tliod" in sixty proposi tions and demonstration* that the Count Palatine of Neuhiiix imutt be chosen king of the Pole*. -^
* De Srlrntin Vmvertali ten Calrulo Phllotophico (U>«4). ' * The author of a Compendium Univrrtalium sen Metaphyiicu KurlUIn*
regular
porters.
The Renaissance : Natural Science Period. [Part IV.
of Leibniz in numerous supporters. 1 So, too, Leibniz busied himself to an extraordinary degree with the thought of a characteristica uni versalis, and a method of philosophical calculus. 2
The essential outcome of these strange endeavours was, that an attempt was necessarily made to establish those highest truths, from the logical combination of which all knowledge was to be deduced. So Leibniz, like Galileo and Descartes, must proceed to search out that which, as immediately and intuitively certain, forces itself upon the mind as self-evident, and by its combinations grounds all derived knowledge. In the course of these reflections Leibniz stumbled upon the discovery3 (which Aristotle had made before him), that there are two completely different kinds of this intuitive knowledge : universal truths self-evident to reason, and facts of experience. The one class has timeless validity ; the other, validity for a single instance : viritis iternelles and vtrite's de fait. Both have in common that they are intuitively certain, i. e. are certain in them selves and not by deduction from anything else ; they are called, therefore, prima veritates, or, also, primes possibiiitates, because in them the possibility of all that is derivative has its ground. For the " possibility " of a conception is known either by a " causal definition " which derives the same from the first possibilities, that is, a priori; or by the immediate experience of its actual existence, that is, a, posteriori.
These two kinds of "primitive truths" — the rational and the empirical, as we see — Leibniz attached in a very interesting manner to the two Cartesian marks of intuitive self-evidence, clearness and distinctness. To this end he shifts to a slight extent the meaning of both expressions. 4 That idea is clear which is surely distin guished from all others and so is adequate for the recognition of its object; that idea is distinct which is clear even to its particular constituent parts and to the knowledge of their combination. According to this, the a priori, "geometrical" or "metaphysical" eternal truths are clear and distinct ; while on the other hand the a posteriori, or the truths relating to facts, are clear, indeed, but not distinct. Hence the former are perfectly transparent, conjoined with the conviction of the impossriblity of the opposite, while in the case of the latter the opposite is thinkable. In the case of the former the intuitive certainty rests upon the Principle of Contradic
1 Such attempts had been projected by J. J. Becker (1661 ), G. Dalgarn (1661), Athanasius Kircher (1663), and J. Wilkins ( 1668).
* Cf. A. Trendelenburg, Historische Beitrage zu Philosophic, Vols. II. , III. 8 Meditationes de Cognitions Veritute et Idris (1684).
* lb. at the beginning, Erd's. ed. , p. 79.
Chap. 2, § 31. ] Substance and Causality. 399
twn; in the case of the latter the possibility guaranteed by the actual fact needs still an explanation in accordance with the Prin
ciple of Sufficient Reason.
At the beginning, Leibniz intended this distinction only with
reference to the imperfection of the human understanding. In the case of rational truths we see into the impossibility of the opposite ; with empirical truths this is not the case, and we must content our selves with establishing their actuality : ' but the latter also, in the natura rerum and for the divine understanding, are so grounded that the opposite is impossible, although it remains thinkable for us. If Leibniz compared this distinction with that of commensur able and incommensurable magnitudes, he meant at the beginning that incommensurability lies only in man's limited knowing capacity. But in the course of his development this antithesis became for him an absolute one ; it gained metaphysical significance. Leibniz now distinguished realiter between an unconditional necessity, which involves the logical impossibility of the opposite, and a conditional necessity, which has " only " the character of a matter of fact.
He divided the principles of things into those of which the opposite is unthinkable, and those of which the opposite is thinkable : he dis tinguished metaphysically, also, between necessary and contingent truths. This, however, cohered with metaphysical motives, which arose from an after-working of the Scotist theory of the contin gency of the finite, and overthrew the geometrical method.
§ 31. Substance and Causality.
The real [as contrasted with formal] result of the new methods was in metaphysics, as in natural science, a transformation of the fundamental ideas of the nature of things, and of the mode of their connection in the processes of Nature : the conceptions of sub stance and causality acquired a new content. Hut this change could not proceed so radically in metaphysics as in natural science. In this latter more limited realm, after the Galilean principle had once been found, it was possible in a certain measure to begin ab ovo and produce a completely new theory : in the more general philo sophical doctrines the power and authority of tradition were much too great to make it possible or permissible that it should be completely set aside.
This distinction asserted itself already in connection with the delicate relation sustained to religious conceptions. Natural science
1 The Aristotelian distinction of Mti and An,
400 The Renaissance : Natural Science Period. (Taet IV.
could isolate itself absolutely from theology, and maintain toward it an attitude of complete indifference : metaphysics, by its concep tion of the deity and by its theory of the mental or spiritual world, was brought again and again into hostile or friendly contact with the religious sphere of ideas. A Galileo declared that the investigations of physics, whatever their result might be, had not the least thing to do with the teaching of the Bible,1 and a Newton was not prevented by his mathematical natural philosophy from burying himself with the most ardent piety in the mysteries of the Apocalypse. But the metaphysicians, however indifferent their thought as regards religion, and however strictly they might prose cute their science in the purely theoretical spirit, were still always obliged to consider that they had to do with objects concerning which the Church doctrine was fixed. This gave modern philosophy a somewhat delicate position : mediaeval philosophy had brought to the objects of Church dogma an essentially religious interest of its own as well ; modern philosophy regarded them, if at all, from the theoretical standpoint only. Hence those felt themselves most secure who, like Bacon and Hobbes, restricted philosophy also entirely to natural research, declined to enter upon a metaphysics proper, and were willing to let dogma speak the only words with regard to the deity and the super-sensible destiny of man. Bacon did this with large words behind which it is difficult to recognise his true disposition ; 2 Hobbes rather let it be seen that his natural istic opinion, like the Epicurean, saw in ideas as to the supernatural a superstition resting upon a defective knowledge of Nature, — a superstition which by the regulation of the state becomes the bind ing authority of religion. 8 Much more difficult, however, was the position of those philosophers who held fast to the metaphysical conception of the deity in their very explanation of Nature ; Des cartes' whole literary activity is filled with an anxious caution directed toward avoiding every offence to religion, while Leibniz could attempt to carry through in a much more positive manner the conformity of his metaphysics to religion ; and on the other hand the example of Spinoza showed how dangerous it was if philosophy openly brought to the front the difference between its conception of God and the dogmatic conception.
1. The main difficulty of the case inhered in the circumstance that the new methodical principle of mechanics excluded all tracing of
i Cf. the letter to the Grand Duchess Christine, Op. II. 26 ft*.
s De Augm. Scient. IX. , where the supernatural and incomprehensible is set
forth as the characteristic and serviceable quality of faith. * Leviathan, I. 6 ; cf. the drastic expression, ib, IV. 32.
Chap. 2, § 31. ] Substance and Causality : Bacon. 401
corporeal phenomena back to spiritual forces. Nature was despiritu- alised ; science would see in it nothing but the movements of smallest bodies, of which one is the cause of the other. No room remained for the operation of supernatural powers. So first of all, at one stroke, magic, astronomy, and alchemy, in which the Neo-Platonic ghosts and spirits had held sway, became for science a standpoint of the past Leonardo had already demanded that the phenomena of the external world should be explained by natural causes only ; the great systems of the seventeenth century without exception recognise only such, and a Cartesian, Balthasar Bekker, wrote a book ' to show that in accordance with the principles of modern science, all appear ances of ghosts, conjurations, and magic arts must be reckoned as injurious errors, — a word of admonition which was very much in
place in view of the luxuriant superstition of the Renaissance.
But with the spirits, teleology, also, was obliged to give place.
The explanation of natural phenomena by their purposiveness always came ultimately in some way or other to the thought of a spiritual creation or ordering of things, and so was contradictory to the principle of mechanics. At this point the victory of the system of Democritus over the natural philosophy of Plato and Aristotle was most palpable ; this, too, was emphasised most forcibly by the new philosophy. Bacon counted the teleological mode of regarding Nature as one of the idols, and, indeed, as one of the dangerous idols of the tribe, — the fundamental errors which become a source of illusion to man through his very nature : he taught that
philosophy has to do only with formal or efficient causes, and ex pressed his restriction of philosophy to physics and his rejection of metaphysics precisely by saying that the explanation of Nature is
if it concerns causm efficientes, metaphysics if it concerns causae finale*} In the case of Hobbes, who was the disciple of Bacon and Galileo, the same view is self-explaining. But Descartes, also, desires to see all final causes kept at a distance from the explanation of Nature — he declares it audacious to desire to know the purposes of God. ' Much more open, and keenest by far, is the
polemic of Spinoza* against the anthropomorphism of teleology. In view of his idea of God and God's relation to the world, it is absurd to speak of ends of the deity, and especially of such as have reference to men ; where all follows with eternal necessity from the essential nature of the deity, there is no room for an activity accord ing to ends. The English Neo-Platonists, such as Cudworth Shd
« Balthaur Bekker (1634-1898), De Betoeerte Wereld (1690). * De Angm. III. 4. > Med. IV.
* Cf. principally Kih. I. Append.
physics
402 The. Renaissance : Natural Science Period. [Part IV.
Henry More, combated this fundamental mechanico-antiteleological feature of the new metaphysics with all the eloquence of the old arguments, but without success. The teleological conviction was obliged to renounce definitively the claim of affording scientific explanation of particular phenomena, and only in the metaphysical conception of the whole did Leibniz (cf. below, No. 8), and similarly a part of the English students of Nature, find ultimately a satisfac
tory adjustment between the opposing principles.
With the exclusion of the spiritual from the explanation of
Nature, still a third element of the old view of the world fell away, viz. the thought of the difference in kind and in value of the spheres of Nature, as it had been embodied most distinctly in the Neo-Platonic graded realm of things, following the ancient Pythagorean precedent. In this respect the fantastic natural philosophy of the Renaissance had already done a forcible work of preparation. The Stoic doctrine of the omnipresence of all sub stances at every point of the universe had been revived by Nicolaus Cusanus ; but it was in connection with the victory of the Coperni- can system, as we see in Bruno, that the idea of the homogeneity
of all parts of the universe first completely forced its way to recogni
tion. The sublunary world could no longer be contrasted as the realm of imperfection, with the more spiritual spheres of the stellar heaven; matter and motion are alike in both. It was from this thought that Kepler and Galileo proceeded, and it became complete when Newton recognised th« identity of force in the fall of the apple and the revolution of the stars. For modern science, the old distinction in essence and in value between heaven and earth exists no longer. The universe is one in nature throughout. This same view, moreover, presented itself in opposition to the Aristotelian and Thomistic development system of Matters and Forms. It did away with the whole army of lower and higher forces — the much combated qualitates occulta; ; it recognised the mechanical principle of motion as the only ground of explanation for all phenomena, and therefore, removed also the distinction in principle between the ani mate and the inanimate. Though here Neo-Platonism had co operated toward overcoming this antithesis by its view of the animation of the entire universe, the reverse task now arose for the Galilean mechanics, namely, that of explaining mechanically the phenomena of life also. The discovery of the mechanism of the circulation of the blood by Harvey l (1626) gave to this tendency a
1 In which he had been anticipated by Michael Servetus (burned 1553 in Geneva by Calvin's instrumentality).
•
Chap. 2, §31. ] Substance and Causality: Descartes, Locke. 403
vigorous impulse ; Descartes expressed it in principle in his state ment that the bodies of animals are to be regarded scientifically as most complex automata, and their vital activities as mechanical
Hobbes and Spinoza carried out this thought more exactly ; a zealous study of reflex motions began in the medical schools of France and the Netherlands, and the conception of the soul as vital force became completely disintegrated. Only the Platonists and the adherents of the vitalism of Paracelsus and Boehme, such as Van Hehnont, held fast to this conception in the old manner.
This mechanistic despiritualisation of Nature corresponded completely to that dualistic theory of the world, which from episte- mological motives had been in course of preparation in terministic Nominalism, — the theory of total difference between the inner and the outer icorld. To the knowledge of their qualitative difference was now added that of their real and causal separateness. The world of bodies appeared not only quite different in kind from that of mind, but also as entirely sundered from in its existence and in the course of its motions. The doctrine of the intellectuality of the sense qualities, revived in the philosophy of the Renaissance by the Humanists, had contributed an extraordinary amount toward sharpening the above antithesis. The doctrine tliat colours, tones, smells, tastes, and qualities of pressure, heat, and touch are not real qualities of things, but only signs of such in the mind, had passed over from the Sceptical and Epicurean literature into most of the doctrines of modern philosophy with repetition of the ancient illustrations. Vives, Montaigne, Sanchez, and Campanella were at one in this Galileo, Hobbes, and Descartes revived the teaching of Democritus, that to these qualitative differences of perception noth
ing but quantitative differences correspond in the natura rerum, and this in such way that the former are the inner modes of mentally representing the latter. Descartes regarded sense qualities as ob scure and confused ideas, while the conception of the quantitative determinations of the outer world, on account of its mathematical character, was for him the only clear and distinct idea of them.
According to Descartes, therefore, not only the sensuous feelings, but also the contents of sensation, belong not to the spatial, but to the psychical world only, and represent in this sphere the geomet rical structures of which they are the signs. In our examination of an individual object we can,1 to be sure, gain a knowledge of this
Ct. Med. VI. which allows pcrliapt the plainest view of the very clow relation which I>>-«c»rt< »' [I'lvsicil ■<•arch had t<>experience.
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404 The Renaissance : Natural Science Period. [Part IV.
true mathematical essence of bodies only by the aid of perceptions, and in these perceptions the true mathematical essence is always alloyed with the qualitative elements of the "imagination. " But just in this consists the task of physical research, to dissolve out this real essence of bodies from the subjective modes of our mental representation by means of reflection upon the clear and distinct ele ments of perception. John Locke, who later adopted and made popular this view of Descartes, designated ' those qualities which belong to bodies in themselves as primary, and called those sec ondary, on the other hand, which belong to a body only by virtue of its action upon our senses. 2 Descartes allowed as primary qualities only shape, size, position, and motion, so that for him the physical body coincided with the mathematical (cf. below, No. 4). In order to maintain a distinction between the two, Henry More,3 on the con trary, demanded that impenetrability, regarded as the property of filling space, should also be reckoned to the essential nature of bodies, and Locke,4 in accordance with this view, took up " solidity " into the class of primary qualities.
With Hobbes 5 these thoughts become modified more in accordance with the terministic conception. He regards space (as phantasma rei existentis) and time (as phantasma motus) as also modes of men tal representation, and it is just because we can therefore construct these ourselves that mathematical theory has the advantage of being the sole rational science. But instead of drawing phenomenalistic conclusions from this premise, he argues that philosophy can treat only of bodies, and must leave everything spiritual to revelation. Scientific thought consequently consists, for him, only in the imma nent combination of signs. These are partly involuntary in percep tions, partly arbitrary in words (similarly Occam, cf. § 27, 4). It is only by means of the latter that general conceptions and proposi tions become possible. Our thinking is hence a reckoning with verbal signs. It has its truth in itself and stands as something completely heterogeneous by the side of the outer world to which it relates.
3. All these suggestions become compressed in the system of Descartes to form the doctrine of the dualism of substances. The analytic method was intended to discover the simple elements of reality which were self-explanatory and not susceptible of farther
1 Essay, Human Understanding, II. 8, § 23 f.
a As tertiary qualities, Locke added further the " powers " for the operation of one body upon others.
•Desc. (Euv. (C), X. pp. 181 ff.
« Essay, II. 4.
6 Human Nature, chs. 2-6 ; Leviathan, cha. 4 ff.
Chap. 2, § 31. ] Substance and Causality : Hobbes, Descartes. 405
deduction. Descartes discovered that all that can be experienced is a species either of spatial or of conscious Being or existence. Spa- tiality, or the quality of filling space, and consciousness (" extension " and "thought" according to the usual translation of extensio and cogi- tatio) are the ultimate, simple, original attributes of reality. All that is is either spatial or conscious. For these two prime predi cates are related disjunctively. What is spatial is not conscious ; what is conscious is not spatial. The self-certainty of mind is only that of the personality as a conscious being. Bodies are real in so far as they have in themselves the quantitative determinations of spatial existence and change, of extension and motion, All things are either bodies or minds ; substances are either spatial or con scious : res extensat and res cogitantes.
The world falls thus into two completely different and completely separated realms : that of bodies and that of minds. But in the background of this dualism there stands in the thought of Descartes the conception of the deity as the ens perfectissimum or perfect sub stance. Bodies and minds are finite things; God is infinite Being. 1 The Meditations leave no doubt as to the fact that Descartes ac cepted the conception of God quite in accordance with the inter
pretation of scholastic Realism. The mind in its own Being, which it recognises as a limited and imperfect one, apprehends with the same intuitive certainty the Reality of the perfect, infinite Being also (cf. above, $ 30, 5). To the ontological argument is added the relation of God and the world in the form brought forward by Nicolaus Cusanus, namely, that of the antithesis of the infinite and the finite. But the above-mentioned relationship with the Realism of the Middle Ages appears most distinctly in the development of metaphysics that succeeded Descartes : for the pantheistic conse quences of this presupposition, which had been carefully held back in the scholastic period, were now spoken out with complete clear ness and sureness. And if we find in the doctrines of Descartes' successors a strong similarity with those which in the Middle Ages could lead but a more or less repressed existence, this is intelligible »-ven without the assumption of a direct historical dependence, merely by the pragmatic connection and the logical necessity of the conclusions.
4- The common metaphysical name of "substance," applied to God in the infinite sense, and to minds and bodies in a finite sense, could not permanently cover the problems which were hidden be-
• So likewise Malebrancbe said (Rrrh. III. 2. 0 a. K. ) that Ood could properly ba called only Celui qui est, be is ritre sans restriction, tout ttre injlni tit vairertei.
406 The Renaissance : Natural Science Period. [Part IV.
neath it. The conception of substance had come into a state of flux, and needed " further re-shaping. It had almost lost touch with the idea of thing," the category of inherence ; for just the combi nation of a multiplicity of determinations into the idea of a unitary concrete entity, which is essential to this category, was completely lacking in Descartes' conception of finite substances, since these were held to be characterised by one fundamental quality, spatiality or consciousness. All else that was found in substances must there fore be regarded as a modification of its fundamental quality, of its attribute. All qualities and states of bodies are modes of their spa tiality or extension: all qualities and states of mind are modes of consciousness (modi cogitandi).
It is involved in this that all particular substances belonging to either class, all bodies on the one hand and all minds on the other, are alike in their essence, their constitutive attribute. But from this it is only a step farther to the idea in which this likeness is thought as metaphysical identity. All bodies are spatial, all minds are conscious ; individual bodies are distinguished from one another only by different modes of spatiality (form, size, situation, motion) ; individual minds are distinguished from one another only by differ ent modes of consciousness (ideas, judgments, activities of will). Individual bodies are modes of spatiality, individual minds are modes of consciousness. In this way the attribute obtains meta physical preponderance over individual substances, which now appear as its modifications ; the res extensas become modi extension's; the res cogitantes, modi cogitationis.
Descartes himself drew this conclusion only in the domain of natr ural philosophy, to which in general he restricted the carrying out of his metaphysical doctrine in its principles. Here, however, the general conception of modification took on, of itself, a definite sig nificance, and one capable of apprehension by perception or imagina tion, viz. that of limitation (determinatio) . Bodies are parts of space, limitations of the universal space-filling quality or extension. 1 Hence for Descartes the conception of body coincides with that of a limited spatial magnitude. A body as regards its true essence, a portion of space. The elements of the corporeal world are the " corpuscles,"
Cf. Print. Phil. II. f. , where, at the same time, appears quite clearly that this relation of the individual body to universal space made equivalent to that of individual and species.
For the corpuscular theory, Descartes found many suggestions in Bacon, Hobbes, Basso, Sennert, and others. The variety in the development of this theory, which rests upon the dialectic between the mathematical and the physi cal momenta, has more interest for natural science than for philosophy. An excellent exposition found in Lasswitz, GescMchte der Atomistik.
is
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is,
Chap. 2, § 31. ] Substance and Causality : Malebrancfie. 407
i. e. the firm spatial particles which realiter are no longer divisible : as mathematical structures, however, they are infinitely divisible; that is, there are no atoms. From these presuppositions follow, likewise, for Descartes, the impossibility of empty space, and the infinitude of the corporeal world.
For the mental world the analogous claim was pronounced by Malebranche. In connection with the epistemological motives (cf. below, No. 8) which made it seem to him that no knowledge of things is possible except in God, he came ' to the conception of the raisou universelle, which, as being alike in all individual minds, can not belong to the modes of the finite mind, but is rather that of which finite minds are themselves modifications, and can, just on this account, be none other than an attribute of God. God is in so far the " place of minds " or spirits, just as space is the place of bodies. Here, also, as the expression proves, the relation which obtains in conceptions between the universal and the particular underlies the thought, and following the analogy of the Cartesian conception of space and body this relation is thought in percep tional or picturate terms as participation. * All human insight is a participation in the infinite Reason, all ideas of finite things are but determinations of the idea of God, all desires directed toward the particular object are but participations in that love toward God as the ground of its essence and life, which necessarily dwells in the finite mind. To be sure, Malebranche came into a very critical situation by thus making the finite mind disappear completely in the universal divine mind, as its modification. For how, in accord ance with this, should he explain the self-subsistence and self- activity which it seemed were quite notoriously present in those inclinations and volitions of man which opposed God ? In this difficulty nothing availed but the word " freedom," in using which Malebranche was indeed obliged to confess that freedom was an impenetrable mystery. 3
5. In this course of thought pursued by Malebranche appears clearly the inevitable logical consistency with which the attributes, which were regarded by Descartes as the common essence belonging to either of the two classes of finite substances, could ultimately be thought only as the attributes of the infinite substance or deity. Hut precisely in this point consists the fundamental motive of Spi- nozism, which developed along this line out of Cartesianism directly
and at the outset, and at the same time developed to the farthest
1 Rtck. de la Vtr. III. 2, 8 ; Sntret.
